Electronic determination of centres of rotation produced by orthodontic force systems

1990 ◽  
Vol 12 (3) ◽  
pp. 272-280 ◽  
Author(s):  
E. Pedersen ◽  
K. Andersen ◽  
P. E. Gjessing
Keyword(s):  
Orthodontic Force ◽  
Force Systems

Experimental Studies of Force Systems on Steered Agricultural Tyres

1966 ◽  
Vol 181 (1) ◽  
pp. 133-148 ◽  
Author(s):  
P. A. Taylor ◽  
R. Birtwistle
Keyword(s):  
Experimental Determination ◽  
Experimental Studies ◽  
Soil Surface ◽  
Slip Angle ◽  
Vertical Load ◽  
Force Systems

The paper reports the experimental determination of the force systems acting on free-rolling 7–50 times 16 agricultural tyres, measured with a six-component suspension of the test wheel. Multivariate experimentation techniques were used involving five variables: slip angle, camber, vertical load, tyre pattern and land or furrow operation. The results are presented as three force and three moment components; other methods of representation are discussed briefly. Although the side or cornering force depends on many factors, particularly the soil surface, and is therefore difficult to predict, it is suggested that the draught force (i.e. resistance in the direction of motion) can be expressed as a function of slip for all surfaces.

Simulation of Physiological Loading in Total Hip Replacements

2006 ◽  
Vol 128 (4) ◽  
pp. 579-587 ◽  
Author(s):  
A. Ramos ◽  
F. Fonseca ◽  
J. A. Simões
Keyword(s):  
Bending Moment ◽  
Median Plane ◽  
Coronal Plane ◽  
Equilibrium System ◽  
Element Analysis ◽  
Physiological Loading ◽  
Hip Replacements ◽  
Force Systems ◽  
Direction Component

The determination of biomechanical force systems of implanted femurs to obtain adequate strain measurements has been neglected in many published studies. Due to geometric alterations induced by surgery and those inherent to the design of the prosthesis, the loading system changes because the lever arms are modified. This paper discusses the determination of adequate loading of the implanted femur based on the intact femur-loading configuration. Four reconstructions with Lubinus SPII, Charnley Roundback, Müller Straight and Stanmore prostheses were used in the study. Pseudophysiologic and nonphysiologic implanted system forces were generated and assessed with finite element analysis. Using an equilibrium system of forces composed by the Fx (medially direction) component of the hip contact force and the bending moments Mx (median plane) and My (coronal plane) allowed adequate, pseudo-physiological loading of the implanted femur. We suggest that at least the bending moment at the coronal plane must be restored in the implanted femur-loading configuration.

On Dynamically Equivalent Force Systems and Their Application to the Balancing of a Broom or the Stability of a Shoe Box

2004 ◽  
Author(s):  
Just L. Herder ◽  
Arend L. Schwab
Keyword(s):  
Rigid Body ◽  
Center Of Mass ◽  
The Body ◽  
Resultant Force ◽  
Dynamic Equivalence ◽  
Force Systems ◽  
The Stability ◽  
Metacentric Height ◽  
The Given

The stability of a rigid body on which two forces are in equilibrium can be assessed intuitively. In more complex cases this is no longer true. This paper presents a general method to assess the stability of complex force systems, based on the notion of dynamic equivalence. A resultant force is considered dynamically equivalent to a given system of forces acting on a rigid body if the contributions to the stability of the body of both force systems are equal. It is shown that the dynamically equivalent resultant force of two given constant forces applies at the intersection of its line of action and the circle put up by the application points of the given forces and the intersection of their lines of action. The determination of the combined center of mass can be considered as a special case of this theorem. Two examples are provided that illustrate the significance of the proposed method. The first example considers the suspension of a body, by springs only, that is statically balanced for rotation about a virtual stationary point. The second example treats the roll stability of a ship, where the metacentric height is determined in a natural way.

The Determination of Equilibrium Configurations of Spring-Restrained Mechanisms Using (4 × 4) Matrix Methods

1967 ◽  
Vol 89 (1) ◽  
pp. 87-93 ◽  
Author(s):  
D. F. Livermore
Keyword(s):  
Kinematic Chain ◽  
External Loading ◽  
Matrix Methods ◽  
Kinematic Chains ◽  
Equilibrium Configurations ◽  
Force Systems ◽  
Velocity Information ◽  
Equilibrium Analyses ◽  
External Loads

A spring-restrained, multiple-loop, multiple-degree-of-freedom kinematic chain will normally have one or more stable equilibrium configurations when steady external loads are applied to it. The “kinematic equivalent” of a vehicle and its suspension linkages is a common example of such a system. Changes in external loading due to cornering, braking, and so on, can produce important changes in the equilibrium configuration of the suspension. This paper presents a general method for determining the equilibrium configurations of spring-restrained, kinematic chains under the action of steady external loading. The iterative (4 × 4) matrix method of displacement analysis, previously developed for single-loop chains, is extended to complex chains and is used to determine the displacement and velocity information required for equilibrium analyses. The final results are general computer programs which will determine displacement and/or equilibrium configurations for simple or complex mechanism systems wherein the applied force systems may be considered conservative.

Tissue Reaction to Orthodontic Force Systems. Are we in Control?

2021 ◽  
pp. 129-138
Author(s):  
Birte Melsen ◽  
Michel Dalstra ◽  
Paolo M. Cattaneo
Keyword(s):  
Tissue Reaction ◽  
Orthodontic Force ◽  
Force Systems
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